Shroud for fuel burners



Feb. 23, 1960 R, D, REED 2,925,858

SHROUD FOR FUEL BURNERS Filed Jan. 14, 1957 INVENTOR foam afge-0,

I @BY ATTORNEY f' 2,925,858 Ice a Patented Feb. 23, '1960 sHRoUD Fon FUEL URNERs Robert D. Reed, Tulsa, Okla., assignor to John Zink Company, Tulsa, Okla., a corporation of Delaware Application January 1.4, 1957, Serial No. 634,005

14 Claims. (Cl. 158-1) t The present invention pertains to a shroud for fuel burners and is designed to facilitate the burning of liquid fuels and those which are heavy or viscous but the shroud also has utility for yburners supplied with gaseous fuels.

An yobject of the invention is to provide a shroud for a fuel burner or nozzle so shaped as to provide Passages orrchannels between ribs thereof for return of hot gases from` the burning fuel to the vicinity of the burner tip to promote improved vaporization of the liquid fuel and maintenance of kindling and to stabilize burning of the fuel.

A more specific object of the invention is to provide shrouding means for a fuel burner having circumferentiallyspaced ribs extending lengthwise vtherewithin forming channels between the ribs through which heat developed during combustion of the fuel within the shroud 2 fuels and the burner tip 11 may be of a conventional type for cil supplied thereto in laccordance with: the prac'- tice in the ant. The discharge ports 12 are larranged in a circular outline as shown in Fig. 1. The axes of the discharge ports diverge from each other so as to deliver atomized liquid fuel in a conical pattern to provide a burning flame somewhat as represented by the phantom lines of Fig. 4. The discharge of liquid fuel and steam through the ports 12 sets up a low pressure area aft and near the burner tip. The dame of the vaporized fuel does not extend to the ports 12 andA in general takes place beyond the line 15. The opening 10 is larger thanr the vburner nozzle so that air may move over the burner tip in the direction of the arrows 14 (Fig. 2).

'I'he shroud is provided with a cylindrical exterior surface 16 'and the upstream end 17 thereof is arranged in a plane at right angles to the periphery of the shroud. The circumference of the shroud and the upstream end face 17 may be covered with sheet metal. The opening 10 is of cylindrical configuration and is arranged coaxially with the periphery ofthe shroud.

The shroud may be regarded as being generally of `cup-shape. In an area between adjacent ribs the shroud includes a Wall 18 (Fig. 2) having inner surfaces 19 substantially parallel with the periphery 16 throughout l a major .portion of the length of the shroud. The straight returns through the passages provided by the channels l l and is delivered to annular areas spaced about the ame `immediately forward and adjacent the burner tip or no le.

nother object of the invention is to provide a shroud for a' fuel burner having circumferentially spaced ribs therein forming channels between the ribs with the cross sectional areas of the channels increasing in area in proceeding towards the upstream end of the shroud to facilitate lthe return movement of heat to a position ad- Y Ajacent the burner tip.

A Still further object of the invention is to provide shroud means for a fuelburner wherein the inner edges of the ribs define a conical outline which is substantially the sameas the flared cone of burning fuel so that the ame produced sweeps closely over but not upon the inner edges of the ribs to thereby substantially close the passages -between the ribs for .the return of hot gases vand air to the vicinity of the burner tip or nozzle.

Other objects and 4features of the invention will be appreciated and become apparent as the present disclosure proceeds yand upon consideration of the accompanying drawing and the following detailed description wherein an embodiment of the invention is disclosed.

In the drawing:

Fig. 1 is a plan view of a burner shroud exhibiting `the invention and depicting one type `of burner tip that may be employed in association therewith.

Fig. 2 is an axial sectional view taken on the line 2-2 of Fig. l.

Fig. 3 is a similar view 'taken on the section 3--3 of Fig. l.

Fig. 4 is a view illustrating the flame pattern and the manner in which heat is returned to the proximity of the burner tip.

The invention is directed to a shroud for fuel burners and it Amay be formed of any suitable material and preferably as a ceramic or refractory member of one piece construction. The shroud is provided with a cylindrical opening 10 in the upstream end thereof for accommodating a fuel burner tip or nozzle 11. The shroud has particular utility in connection with a burner for liquid character .of each surface 19 continues in proceeding upstreamof the shroud where it merges with an arcuate surface 21. This arcuate surface 21 is in pant formed on an .annular end wall 22 disposed around the opening 10. The arcuate surfaces 21 merge smoothly with the respectiveI wall ,surfaces 19. The wall surfaces 19 are circumferentially spaced from, each other and'separat'ed by ribs as shown in Fig. 1.

The shroud includes a plurality of circumferentially spaced ribs which project radially inward from the Wall surfaces 19.. These ribs have inclined inner edges 26 which deiine the outline of va cone. The inner edges 26 of the ribs converge toward each other in proceeding upstream of 'the shroud and each inclined surface merges with an inner edge 27 which outline a cylinder as will be appreciated from a consideration of Figs; 2` andi3,-. The axis of the cylinder defined by the rib edges 27 coincides with the axis of the shroud and the edges 27 define a circle which is of slightly larger diameter than the opening 10 (Fig. 1).

It will be appreciated that the structure described and shown in the drawing provides for channels or passages between the ribs. The cross sectional area of each passage or channel increases in proceeding towards an upstream end of the shroud as shown in Fig. 2.

In operation and when liquid fuel is discharged through the ports 12 it is atomized and sets up a low pressure area in the vicinity of the burner tip. The atomized fuel upon ignition provides a flame somewhat as shown in phantom lines in Fig. 4. The flame sweeps along the frustro-conical inner edges 26 of the ribs but it does not engage these faces. The llame sweeping close to the inner edges of the ribs substantially closes the channels or passages formed between these ribs. The heat produced by the burning fuel is in part caused to return 4to the vicinity of the burner tip 11 in what may be regarded a regenerative action so as to supply greater quantities of heat to the liquid fuel being discharged from the ports 12 so as to further promote vaporization thereof. Such movement of the hot gases is indicated by the arrows of Fig. 4 and is to some extent induced by the low pressure zone developed in the Vicinity of the nozzle 11. The Iarcuate surfaces at the base of the channels divent the hot gases radially inwardly in directions substantially at ninety degrees with respect to the -axes of the shroud and the burner tip 11. The hot gases are thus delivered Vasignarse Y f -`to. atomized fuel at azone downstream of the'burner A.

ture level downstream of the burner tip. The regeneraz' tive Iaction of the shrouding means makes it possible to supply suflicient heat into the .proximity of the burner so that fuels of higher viscosity than have been possible to burn in the past may be consumed in a fuel burner `equipped with shroud means embodying the invention.

L While the invention has been described with reference to a shroud having a` particular structural shape it will 'be appreciated that changes may be made in the dimensions and arrangement of the various portions and that other materials may be employedin providing a shroud for a [fuel burner. Such changes and others may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

What I claim and desire to secure by Letters Patent is: 1. A shroud for a fuel burner comprising, a generally cup-shaped member having 'an open end directed towards 'an area to be fired, a wall forming the upstream end of said member having an opening therethrough, a burner mounted within said opening with the tip thereof posiftioned upstream of the downstream face of said Wall, said burner having a plurality of `discharge orices therein with the axes thereof diverging from each other so :as to discharge fuel from the orifices in a substantially conical outline diverging in proceeding towards the openren'd of said member, circumferentially spaced longitudinally extending ribs within said cup-shaped member, an inner edge on each lrib which converges towardsV the axis of said opening in proceeding from the downstream end of said member, said inner edges being at such an angle that the periphery of the conical'outline of burning fuel 1 2. A shroud for a fuel burner comprising, a generally cup-shaped member having an open end directed towards an area to be fired, a wall forming the upstream end of said member having an opening therethrough, said wall having a downstream face at right angles to `the aXis of said opening, a burner mounted within said opening with the tip thereof positioned upstream of said downstream face, said burner having ya plurality of `discharge 'orices therein with the axes thereof diverging from each other so as to discharge fuel from the orifices in a substantially conical outline divergingin proceeding towards the open end of said member, circumferentially spaced longitudinally extending ribs within said cupshapedv member, an inner edge on each rib which converges ltowards the axis of said opening in proceeding 4from kthe downstream end of said member, said inner edges being at such an angle that the periphery of the conical outline of burning fuel sweeps along said inner edges of said ribs, said ribs in cooperation with the inner surfaces of the cup-'shaped member between the ribs .forming circumferentially'spaced channels extending longitudinally of said member, arcu- .ate wall vrSurfaces carried by said cup-shaped member be- -tween upstream ends of said ribs 'merging with the downstream vface of said end wall, and each rib adjacent the 'upstream end of the cup-shaped member having an edge surface which is substantially parallel to the axis of said opening and dening a circular outline. y

3. A shroud according to claim 2 wherein the circular outline of edges on said ribs is of larger diameter -than that of said opening. l I

4. A shroud according to yclaim 2 whereinthefedge -portions of the ribs which are parallel to the axisof'said opening constitute minor lengths of the ribs.

References Cited in the file of this patent UNITED STATES `PATENTS 1,699,732 Balmat `ian. 22, 1929 2,044,511 Ryschliewitsch June 16, 1936 2,207,010 Hopkins July 9, 1940 2,220,572 Knupp Nov.v 5, l1940 2,275,555 Power Mar. '10, 1942 2,424,765 McCollum y.luly 29, 1947 2,532,740 Speer Dec. 5, 1950 FOREIGN PATENTS 551,568 Great Britain Mar. 1, 1943 

